Apparatus for flushing cooling systems of marine engines are well known in the art, and are commercially available. Typically, such apparatus employs two heads, or sealing members, mounted in confronting relationship on a bracket for disposition over the cooling water intake ports of the engine housing. The heads (or at least one of them) are adapted to receive fresh water and direct it through an underlying intake port; mechanical means is conventionally employed to hold the heads in place.
Representative of the prior art on engine-flushing assemblies of the kind described are the following U.S. patents: U.S. Pat. No. 4,246,863, issued Jan. 27, 1981; No. 4,359,063, issued Nov. 16, 1982; No. 4,540,009, issued Sep. 10, 1985; No. 4,973,276, issued Nov. 27, 1990; and No. 5,051,104, issued Sep. 24, 1991.